极端气象气候条件下土地利用变化的水文水资源效应研究——以东江流域为例

Effects of Land-use and Land-cover Change(LUCC)on Hydrology and Water Resources under Weather and Climate Extremes--a Case Study of the Dongjiang River Basin,Southeastern China

近年来,人类活动导致的土地利用变化对流域水文过程具有重要影响已为学界所公认。然而,在不同气象灾害条件下(如暴雨和干旱),土地利用变化的水文效应是否会有所放大,仍未得到充分研究。气候变化正导致许多地区极端气象气候事件增多,深入研究暴雨和干旱条件下的土地利用变化的水文效应具有重要意义。本文以东江流域为例,基于SWAT水文模型,针对不同土地利用变化情景,对东江流域水文过程响应分别进行了日尺度和月尺度模拟,重点研究发生强降雨及干旱时土地利用变化对流域水文过程的影响。结果表明,城镇用地和林地扩张对东江流域月径流量的影响相对较小,主要表现为城镇用地面积的增加使得径流年内分配不均加剧。发生强降雨时,城镇用地和林地扩张各自对日径流的增强和减弱效应显著,且影响效应随城镇用地和林地面积的增大而增大。发生不同程度干旱时,城镇用地和林地扩张对蓝、绿水资源总量的影响较小;发生中度干旱时,土地利用变化对蓝绿水资源的整体影响最大。

In recent years,it has been widely recognized that land-use and land-cover change(LUCC)caused by human activities has significantly affected the hydrological process and water resources of river basins.However,whether the hydrological and water resource effects of LUCC are amplified under weather and climate extremes(such as heavy rainfall and drought)has not been fully studied.Climate change is leading to an increase in extreme meteorological and climatic events in many regions of the globe,and thus it is of great significance to study the hydrological and water resource effects of LUCC under heavy rainfall and drought conditions.In this study,taking the Dongjiang River Basin as an example,we utilized the Soil and Water Assessment Tool(SWAT)model to simulate the response of hydrological processes and water resources for different LUCC scenarios on both daily and monthly scales in the Dongjiang River Basin.The results suggest that the expansion of urban(×2.5,5.0 times)and forested(+10%,13%)areas has relatively little impact on the monthly runoff in the studied basin.However,when heavy rainfall occurs,an expansion of urban and forested areas have significant increase and decrease effects on daily runoff,respectively,and the magnitudes of the effects increase with the expansion of urban and forested areas.When different degrees of drought occur,the expansion of urban(×2.5,5.0 times)and forest(+10%,13%)has relatively limited impact on the total amount of blue/green water resources.When moderate drought occurs,LUCC displays the greatest overall impact on blue/green water resources.